In order to prepare phenol prior to purifying phenol, a method for separately preparing phenol and acetone using an indirect oxidation reaction, etc. and using cumene, which is commonly synthesized from a phenol resin, nylon-6, an epoxy resin, a polycarbonate resin and a solvent, as a raw material, as shown in Reaction 1 below is used.

The reaction product thus prepared includes impurities, and in order to remove thereof, a separation process with a plurality of steps which consume a large amount of energy is required. For example, a hydrocarbon removal column (HRC) for separating hydrocarbon materials having a similar boiling point as phenol via azeotropic distillation uses high pressure (HP) at the bottom thereof, and a low pressure (LP) of a side reboiler, and an upper heat source of a crude phenol column (CPC) and a phenol finishing column (PFC) is used.
On the contrary, the hydrocarbon removal column (HRC) consuming such a large amount of energy supplies energy (heat source) to reaction parts (1, 2) and a separation part (3) in a phenol preparation process, but has a main downside of losing a heat source due to the presence of uncondensed vapor (6). Accordingly, energy saving consumed in a whole process including minimizing the loss of a heat source by changing operation conditions of various columns such as a hydrocarbon removal column (HRC) is required.
Various methods for purifying phenol are disclosed such that Korean Registration Patent No. 10-0377297 relates to a purification method of phenol which is prepared by a cumene method, and discloses features for improving the performance of a catalyst used during separating phenol by controlling the temperature, the composition, or the like during separating phenol and impurities, and Korean Laid-open Publication Patent No. 10-2006-0130073 also relates to a purification method of phenol, and discloses features for producing a purified phenol steam by decreasing the initial concentration of hydroxyacetone and methylbenzofuran in a phenol steam simultaneously, by contacting a phenol steam containing hydroxyacetone and methylbenzofuran with initial concentrations at 50 to 100° C. with an acidic ion exchange resin. Research for further improvement thereof is conducted from various angles.